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Do you know how the telephone works?

January 05,2022

When I was young, the communication between people was through letters, and the advanced one was telegraph, but it was very expensive.

Later, with the telephone, these traditional contact methods gradually disappeared, and I still vaguely remember the joy when I first touched  the telephone. With the development of science and technology, mobile phones have already become popular, and there may be more advanced things to replace it in the future. Of course, this is another story, because the future is unpredictable.

But you have been using the telephone for so long; do you know the principle of the telephone? How does its receiver and microphone work?

The teacher will explain it to you in detail through this article

The principle of microphone is the same as that of microphone, so let me talk about the principle of microphone. The microphone is transmitted from the vibration of sound to the diaphragm of the microphone , which pushes the magnet inside, and the magnetic field changes when the magnet moves. At this time, the coil will cut the magnetic induction line to form a variable current, which will be sent to the following sound processing circuit for amplification. Obviously, this is magnetic electricity, that is, the principle of electromagnetic induction.

So how does the receiver work?

In fact, the earpiece is also a kind of loudspeaker, which is a very commonly used electro acoustic transducer, and it can be seen in the electronic and electrical equipment that make sounds. Loudspeaker is a device that converts electrical signals into acoustic signals. It is mainly composed of fixed permanent magnets, coils and cone-shaped paper pots.

When the current as shown in the figure passes through the coil, the coil is attracted by the magnet to move to the left, and when the current in the opposite direction passes through the coil, the coil is repelled by the magnet to move to the right. Since the current passing through the coil is an alternating current, its direction changes constantly, and the coil vibrates back and forth continuously, driving the paper basin to vibrate back and forth, so the speaker makes a sound. Therefore, the principle of loudspeaker is the force exerted by the electrified conductor in the magnetic field, or it can be described as the powerful effect of the magnetic field on the electrified conductor.

To sum up, microphone and microphone have the same principle, which is to convert acoustic signals into electrical signals.

The principle is:

electromagnetic induction; the principle of earpiece and loudspeaker is the same, which is to convert electrical signals into acoustic signals. The principle is: the force exerted by the conducting conductor in the magnetic field.